Exposure Compensation from a Single Image

Abstract

We propose a method to convert underexposed/overexposed images to appropriately exposed image from a single image. Digital cameras have a limited dynamic range which is smaller than one in the real world, so that it often takes overexposed/underexposed images. The HDR method synthesizes images with different exposures into an image to improve visibility of a narrow dynamic range image. However, HDR has several limitations to get good images. One of them is difficult to take the appropriate multiple exposed images. Because When taking the multiple exposed images, the camera and object must not move to avoid the ghost effect. The proposed method can improve the narrow dynamic range with a single image. In addition, it can avoid to generate ghost effect in the output image. Our method generates three of the pseudo multiple exposed images from a single image. In the process of generating pseudo high exposed and low exposed image, our method uses gamma correction to adjust luminance of input image. Moreover, gamma correction can enhance the difference between each color channel in the dark or bright area of the input image. Because of gamma correction, the contrast of the input image is properly improved. We utilize the Contrast Limited Adaptive Histogram Equalization (CLAHE) to make the pseudo middle exposed image. Three types of pseudo exposed images generated will be synthesized into an output image which is high quality image as same as HDR image.